Mike Rivers wrote:
Does that mean that Phil actually got the goods on me this time? I
used RF as an example because everyone knows what that is, and it's
possible, if you're sloppy, for both leads going to a differential
input to act as similar antennas. OK, I'll admit that I was right, but
didn't use the best example.

We have been known to have RFI problems around the studio, too.

My usual example when explaining how a differential input works to
reject common mode noise is hum induced from a magnetic field, but that
involves too long an explanation to answer a simplistic question. But I
see that eventually someone did give that explanation.

I'm no electronics expert, so perhaps I'm missing something, but I
thought radio waves were simply (changing) magnetic fields that
induce (changing) electric fields that in turn cause magnetic
fields, and the process repreats until the energy is absorbed
and/or an antenna picks up the signal by having one of those
generations of magnetic field turn into electricity within the
conductor.

The point being, I don't see how there can be a distinction between
hum caused by changing magnetic fields and hum caused by radio.
If the two wires are really close together and the frequency is,
say, 100 Hz, then wavelength is really, really long, and in fact
the distance between the transmitting and receiving antenna is
waaay less than one wavelength. But does that mean it's not
the same thing as radio?

By the way, from what I can dig up, it seems that the US Navy
uses radio at 76 Hz to communicate with submarines. Apparently
the antennas are fairly long, like way over 10 miles long.

- Logan